- Top of page
- What are visual opsins and how do they lead to color vision?
- Microbial rhodopsins enable microorganisms to sense light
- How do opsins regulate the wavelength of their chromophore: Retinal-PSB
- Early model compound studies and rhodopsin mutagenesis studies
- Prediction of the upper limit of red shift and computational studies of the retinal-PSB
- Rhodopsin mimic engineering: Initial efforts
- Full encapsulation of chromophore is crucial
- The second generation rhodopsin mimic surpassed the theoretical limit
- Rhodopsin mimics provide a simpler platform for theoreticians
- Possibility of spectral tuning of opsins?
- Conclusions and outlook
The evolution of a variety of important chromophore-dependent biological processes, including microbial light sensing and mammalian color vision, relies on protein modifications that alter the spectral characteristics of a bound chromophore. Three different color opsins share the same chromophore, but have three distinct absorptions that together cover the entire visible spectrum, giving rise to trichromatic vision. The influence of opsins on the absorbance of the chromophore has been studied through methods such as model compounds, opsin mutagenesis, and computational modeling. The recent development of rhodopsin mimic that uses small soluble proteins to recapitulate the binding and wavelength tuning of the native opsins provides a new platform for studying protein-regulated spectral tuning. The ability to achieve far-red shifted absorption in the rhodopsin mimic system was attributed to a combination of the lack of a counteranion proximal to the iminium, and a uniformly neutral electrostatic environment surrounding the chromophore.